Vibratory finishing machine with screen discharge



Oct. 15, 1968 F. G. BONIFACE 3,405,483

VIBRATORY FINISHING MACHINE WITH SCREEN DISCHARGE Filed Sept. 14, 1966 2Sheets-Sheet 1 Fla. 2.

Oct. 15, 1968 F. G. BONIFACE 3,405,483

VIBRATORY FINISHING MACHINE WITH SCREEN DISCHARGE Filed Sept. 14, 1966 2Sheets-Sheet 2 United States Patent 3,405,483 VIBRATORY FINISHINGMACHINE WITH SCREEN DISCHARGE Frederick George Boniface, HemelHempstead, England, assiguor to Rota-Finish Limited Filed Sept. 14,1966, Ser. No. 579,339 Claims priority, application Great Britain, Sept.15, 1965, 39,486/ 65 Claims. (Cl. 51-163) A known type of apparatus forpolishing or otherwise finishing the surfaces of workpieces by abrasioncomprises a resiliently supported tub disposed with its axisapproximately horizontal, and a rotary vibrator mounted on the tub withits axis parallel to that of the tub. The workpieces together with amass of processing media, such as loose chips of rock or ceramicpellets, are placed in the tub, either with or without a treatingliquid. The circular vibrating movement imparted to the tub by thevibrator not only causes local relative movements between the workpiecesand the media to produce the desired abrasive finishing action, but alsocauses the whole mass of material in the tub to circulate in an orbitalpath around the axis of the tub.

When the desired finishing treatment has been completed, it is necessaryto separate the workpiece from the media and this has hitherto beeneffected either by picking out the individual workpieces by hand as theyare successively brought to the surface by the orbital movement, or bydischarging the mixture of workpieces and media from the tub onto ascreen having openings of such size that it retains the workpieces butallows the media to pass through it, the media being subsequentlyreturned to the tub for the treatment of further workpieces. The firstmethod is of practical use only when the apparatus is employed fortreating workpieces of relatively large size in relatively smallnumbers. The second method, while of general application, is a dirty andtime-consuming operation.

It has also been proposed to separate out the finished workpieces bymeans of a screen which is pivotally or slidably mounted adjacent thetub, so that when desired it can be thrust into the descending part ofthe mass of material in the tub, the screen then intercepting theworkpieces, while the media passes through the screen and continues tocirculate in the tub. With this proposed arrangement it is difiicult tocontrol the rate at which the descending material falls onto the screenand if so much is received that the screen becomes choked with media,the screen must be partially withdrawn from the tub, with the resultthat only a small part of the screen still overhangs the tub and isavailable for elfecting separation. Also, with this proposedarrangement, the screen is necessarily inserted into the upper part ofthe circulating mass, with the result that when a certain proportion ofthe mass has been removed by the action of the screen, the surface ofthe mass remaining in the tub falls below the level of the screen andseparation ceases; the arrangement consequently cannot be used toachieve complete separation of workpieces when the proportion ofworkpieces to media is high, for example if the workpieces constitutemore than of the tub contents.

The vibratory finishing apparatus of the present invention alsocomprises a separating screen which can be brought to extend across thepath of the circulating mass in the tub so that it will intercept theworkpieces, while allowing the media to continue circulating in the tub,and is characterised by the fact that the separating screen is fixed inposition and is brought into the path of the material circulating in thetub by an upward tilting of the tub about an axis parallel to the axisof the tub.

3,405,483 Patented Oct. 15, 1968 "ice With this arrangement the rate atwhich material is received onto the screen can be controlled very simplyby altering the inclination of the tub. Since the principal component ofthe relative movement between the tub and the screen is vertical ratherthan horizontal, a substantial part of the screen overhangs the tub atall times and a partial lowering of the tub to reduce the rate at whichmaterial is received onto the screen results in only a small reductionof the area of screen available for effecting separation. Also, the tubcan be raised sufficiently to bring the screen below the surface of thecirculating material even when the volume of material in the tub hasbeen substantially reduced, thus allowing complete separation ofworkpieces to be obtained even if the workpieces form a high proportionof the tub contents, for example as much as 25%.

A particular form of vibratory, finishing machine in accordance with theinvention is shown by way of exam ple in the accompanying drawings, inwhich:

FIGURE 1 is a vertical cross section through the machine;

FIGURE 2 is a similar view of the machine with the parts in differentrelative positions;

FIGURE 3 is a front view of the machine; and

FIGURE 4 shows a detail of the machine.

In the apparatus illustrated, the tub 1 having the form of a partcylinder disposed with its axis horizontal, is resiliently supported bysprings 2 upon a frame 3, which is pivotally supported at 4 upon astationary frame 5. The frame 3 can be tilted to raise or lower the tubabout an axis parallel to that of the tub by a hydraulic operatingcylinder 6 connected between frames 3 and 5. Secured to the tub is avibrator 7, comprising an eccentrically weighted rotary shaft and anelectric motor for driving this shaft. The curved wall of the tubembraces some 240 of arc and one edge 8 of the opening left in the upperpart of the tub is substantially higher than the opposite edge 9. Thevibrator runs in such a direction that the mass of material in the tub,comprising workpieces 10 and processing media 11 circulates clockwise(as viewed in FIG- URES 1 and 2) and cascades from the upper edgetowards the lower edge. A separating screen 12 extending the full lengthof the tub is mounted on a support 13 secured to the stationary frame 5.The screen may be of mesh material or of any other suitableconstruction, such as a series of parallel rods extending radially ofthe tub. As shown in FIGURE 4 (which is a fragmentary section on alarger scale through the inner margin of the screen), it comprisesradial rods 14, longitudinal rods 15 and a peripheral sheet metal member16 of inverted channel section, which covers and is secured to theupturned ends of the rods 14, 15, thus providing an imperforate rim orretaining wall. The machine may be enclosed in a casing (indicated bythe chain line 17 in FIGURES l and 3) having an opening giving access tothe interior of the tub.

While the finishing treatment is in progress, the cylinder 6 isretracted, so that the parts occupy the positions shown in FIGURE 1 withthe screen 12 above and clear of the circulating mass in the tub. Whenthe processing has been completed and it is desired to extract theworkpieces from the tub, the cylinder 6 is extended to raise the frame3, carrying the tub and its vibrator, into the position shown in FIGURE2, operation of the vibrator being continued, so that the material inthe tub continues to circulate orbitally. The screen 12 now projectsacross the path of the mass as it cascades from the upper to the loweredge of the tub and the workpieces 10 are intercepted by and retained onthe screen while the media passes through the screen and continues tocirculate in the tub. The workpieces collected on the screen may bepicked off by hand, or removed by conveyor means of any kind, or causedto slide off the screen by suitably inclining it. After removal of'thetreated workpieces, the tub is returned to the position shown in FIGURE1 and is then ready to receive a fresh batch of workpieces, which cansimply be placed on the cascading surface of the media and left todistribute themselves through the media.

The removal of the workpieces reduces the total volume of material inthe tub (the workpieces may in practice ac count for 25% by volume ofthe mass in the tub while finishing treatment is in progress) and toensure that so large a proportion of the mass can be separated out inthe way described, the extent of lifting movement effected by thecylinder '6 should be sufiicient to raise the axis of the tub through adistance equal to about one quarter of the diameter of the tub. Toassist in ensuring that the cascading action in the tub remainssubstantially the same throughout the volume change that occurs duringseparation, it has been found advantageous to make the length and thediameter of the tub approximately equal. To the same end, the suspensionsprings 2 are made somewhat stiffer than those previously used inotherwise similar apparatus with a fixed tub.

I claim:

1. A finishing machine comprising a stationary frame, a tilting framesupported on said stationary frame for upward and downward movementabout a horizontal pivot axis between a lowered position and a raisedposition, an open-topped tub for receiving a mixture of parts to befinished and finishing media, said tub being supported for vibration onsaid tilting frame in a position to one side of said pivot axis, arotary vibrator secured to said tub and adapted to subject said tub andits contents to vibration to cause finishing of said parts andcirculation of said mixture about a horizontal axis parallel to saidpivot axis, and a separating screen having openings of a size to permitpassage of said media but not of said parts to be finished, said screenbeing fixedly supported on said stationary frame in a position extendingfrom above said pivot axis to within the open top of said tub, saidscreen extending into the path of the mixture circulating in the tubwhen said tilting frame is in its raised position and said screen beingclear of said mixture when said tilting frame is in its loweredposition.

' 2. A machine according to claim 1 and comprising power means supportedby said stationary frame for moving said tilting frame between itslowered and raised positions.

3. A machine according to claim 1 wherein said tub is of part circularcross section and movement of said tilting frame from its lowered to itsraised position raises the axis of said tub through a distance at leastequal to one quarter of the diameter of said tub.

4. A machine according to claim 1 wherein said tub is of part circularcross section and has an axial length substantially equal to thediameter of said tub.

5. A machine according to claim 1 wherein said screen is inclineddownwardly at an angle to the horizontal in a direction away from saidtub.

References Cited UNITED STATES PATENTS 3,157,004 11/1964 Musschoot 5ll63X 3,161,993 12/1964 Balz 5ll63 HAROLD D. WHITEHEAD, Primary Examiner.

1. A FINISHING MACHINE COMPRISING A STATIONARY FRAME, A TILTING FRAMESUPPORTED ON SAID STATIONARY FRAME FOR UPWARD AND DOWNWARD MOVEMENTABOUT A HORIZONTAL PIVOT AXIS BETWEEN A LOWERED POSITION AND A RAISEDPOSITION, AN OPEN-TOPPED TUB FOR RECEIVING A MIXTURE OF PARTS TO BEFINISHED AND FINISHING MEDIA, SAID TUB BEING SUPPORTED FOR VIBRATION ONSAID TILTING FRAME IN A PORTION TO ONE SIDE OF SAID PIVOT AXIS, A ROTARYVIBRATOR SECURED TO SAID TUB AND ADAPTED TO SUBJECT SAID TUB AND ITSCONTENTS TO VIBRATION TO CAUSE FINISHING OF SAID PARTS AND CIRCULATIONOF SAID MIXTURE ABOUT A HORIZONTAL AXIS PARALLEL TO SAID PIVOT AXIS, ANDA SEPARATING SCREEN HAVING OPENINGS OF A SIZE TO PERMIT PASSAGE OF SAIDMEDIA BUT NOT OF SAID PARTS TO BE FINISHED, SAID SCREEN BEING FIXEDLYSUPPORTED ON SAID STATIONARY FRAME IN A POSITION EXTENDING FROM ABOVESAID PIVOT AXIS TO WITHIN THE OPEN TOP OF SAID TUB, SAID SCREENEXTENDING INTO THE PATH OF THE MIX TURE WHEN SAID TILTING FRAME IS INITS LOWERED POSITION.